How to Grow Viscaria Plants

Viscaria

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An easy-to-grow annual, the viscaria plant is known for its vibrant purple blooms. When planted alone, these erect, stiff-stemmed plants can appear almost weed-like, but together they create a carpet of color.

With varieties referred to as the sticky catchfly, clammy campion, and rose of heaven, viscaria plants are part of the silene family and readily establish from flower seeds--in fact, they are among the easiest plants to grow and maintain.

These flowers are an ideal choice if you happen to live in a warmer climate and can plant them in a spot with abundant sunshine. Consider viscaria plants to add a colorful border to a rock garden, or any other dry areas on your property.

Botanical Name Silene viscaria
Common Name Viscaria, Sticky Catchfly, Clammy Campion, Rose of Heaven
Plant Type Annual
Mature Size 12-18 inches
Sun Exposure Full sun/Part shade
Soil Type Well-drained, sandy, loamy
Soil pH 6.1-7.8
Bloom Time Summer
Flower Color Purple
Hardiness Zones 3-8
Native Area Europe, Canada, Greenland, Iceland, Kazakhstan, Siberia

Viscaria Plant Care

When planting viscaria, you'll have the best results when sowing them in the open ground, although they can be planted in pots and then later transplanted. They should be planted about six inches apart. You can expect to see their gorgeous purple blooms in the summer months (June through August).

Viscaria flowers will generally start off as small, grass-like tufts of foliage, which will eventually reach about five inches tall before producing flowering stalks. The stalks can rise as high as 12 to 18 inches tall (and will have a sticky texture just below the leaf joints). Viscaria plants are usually stiff enough to hold their own weight, but if you've happened to plant one of the taller varieties of viscaria, you may need to provide support.

Best of all, the viscaria flower is actually a plant that can benefit the health of your garden. These plants contain brassinosteroids, often used in plant strengthening formulas and fertilizers, and can help to promote disease resistance and overall health of any flowers planted nearby. However, they can be susceptible to slugs and snails, which can damage the foliage of outdoor plants. 

Light

The viscaria will thrive in both full sun and partial shade. They should ideally receive full sun for at least half of the day.

Though they can tolerate partial shade, bright sunlight will help bring out the plant's vibrant colors and promote stem strength.

Water

Although the viscaria plant is considered to be somewhat undemanding and even drought-resistant, you won't want to let your plants become too dry.

Try to water either in the morning or evening, as opposed to the mid-day, particularly on sunny days. Plus, don't let the soil become waterlogged, as it will promote the risk of root rot and kill the plant.

Soil

Viscaria can grow when planted in a wide range of soils. However, steer clear of heavy, wet soil. A well-drained soil is best, and they will thrive in slightly sandy, loamy soil.

Temperature and Humidity

These are hardy annuals that can tolerate a bit of frost. Some varieties of viscaria have even been known to survive freezing temperatures. However, it's generally best to plant them after the coldest part of the winter has passed.

Fertilizer

The viscaria plant doesn't necessarily require fertilizer, but it can help promote healthy growth. Liquid fertilizer can be used during the summer. For best results, apply monthly throughout the warmer months.

Pruning

While they don't require extensive pruning, viscaria flowers can be deadheaded in order to encourage fuller blooms. The inflorescences can be trimmed to about two inches, and the stems and branches can also be pruned after the flowers have bloomed. Just be sure to time your pruning for before the seeds have matured.

Propagating Viscaria

Viscaria plants can be propagated in a few different ways: seed, offsets, or division. Viscaria plants that are rooted outdoors should freely self-seed.

The best time to start sowing seeds is between February and May. They will take about two weeks to germinate (assuming they're kept in a room between 64 and 68 degrees Fahrenheit). Once the plant begins to produce its grass-like tufts, they can be transplanted to garden beds or plant containers.

Potting and Repotting Viscaria

When planting viscaria in containers, it's important to sow only a few seeds per pot (and thin the seedlings to just one plant per pot). You should also transplant potted plants every couple of years in order to fully replace the soil or provide a larger pot for the root system.